Along with a recent tendency of reducing business trip costs and business trip man hours, transmission systems for carrying out a TV conference using a communication network such as the Internet have become wide spread. In such a transmission system, when a telephone call is carried out between plural transmission terminals, image data and voice data are transmitted therebetween, and thus, a TV conference can be carried out.
Further, thanks to recent expansion of the broadband environment, transmission of image data with high image quality and voice data with high sound quality becomes possible. Thereby, a situation of another person in a TV conference becomes able to be easily understood, and it becomes possible to understand each other by conversation at a high level.
In such a TV conference system, in order to relay content data among TV conference terminals, a relay apparatus is provided in general. In this case, it is known to select a relay apparatus from among plural relay apparatuses depending on attributes of the TV conference terminals participating in the TV conference, for the purpose of load sharing in a communication network or such. For example, it is known that a conference room ID (identification) is allocated to a TV conference terminal, and a relay apparatus is selected based on the conference ID of the TV conference terminal participating in the TV conference (see Japanese Laid-Open Patent Application No. 2006-229416). Thereby, it is possible to average traffic in relay apparatuses, and thus, it is possible to share the load of the communication network to a certain extent.
However, in the above-mentioned TV conference system according to the related art, although it is possible to select a relay apparatus based on the conference ID of the TV conference terminal, it may not be possible to select an optimum relay apparatus depending on plural independent attributes such as a communication network to which the TV conference terminal is connected, an area in which respective transmission terminals are connected with a communication network, and so forth.